Radio direction finder



Oct. 12, 1937. v E BE| |N| 2,095,588

' RADIO DIRECTION FINDER Filed May 15, 1934 INVENTOR ETTORE ELLINI BY JU L ATTORNEY Patented Get. 12, 1937 assists PATEN'E' @FFEQE RADIO DIRECTION FENDER Ettore Bellini, Paris, France, assignor to (lie Gnrale ole Tlgraphie Sans Fil, a corporation of France Application May 15, 1934, Serial No. 725,694 In France July 10, 1933 Claims.

This invention relates to improvements in radiodirection finders or radio-goniometers.

It is a well-known fact that the influence of the hull of a vessel is responsible for errors in 5 the taking of bearings by means of a radiogoniometer installed on shipboard. The sense of this error, which is known as the quadrantal error, is such that the vitiated bearings lie closer to the axis of the vessel than the true bearings. The maximum error occurs whenever the ships axis makes an angle with the directional line to the sending or beacon station of approximately 45, 135, 225 or 315 degrees. The hull of a vessel behaves like a closed loop located in the axis of the vessel. This renders the reception of signals unduly strong in the direction of the vessel axis.

It is likewise known that in order to compensate for this excess of reception or response, there may be disposed about the frame or coil a closed vertical loop having its plane in the axis of the vessel, said loop consisting of a single turn of wire fixed to the masts, halliards, etc. Such a loop may thus have a more or less arbitrary form and it is apt to be unstable, unless its construction is of rather large dimensions. Otherwise its movements or sways due to the action of the wind and the roll of the ship may have an undesirable effect upon the coil of the radiogoniometer.

The above described and well known loop constitutes an imperfect screen or shield which diminishes reception when the coil is in the same axial direction as that of the vessel. However, in order to insure exact compensation it is necessary to regulate the action of this loop with the view to making it equal and opposite to the action of the loop represented by the shell.

This regulation is insured by the insertion of a certain number of convolutions of an inductance coil contained in the compensating loop, and this reduces its screen effect.

However, the said loop connected with the masts, halliards, etc., is cumbersome and fragile.

The object of the present invention consists essentially in the use of two rigid loops having dimensions somewhat larger than those of the radio-goniometer frame, and mounted so that they can be disposed parallel in reference to each other. These loops are also adapted to be fixed on the leftor right-hand side of the frame and at equal distances. By varying the spacing between these loops or by placing them in a sloped position in reference to the frame or coil, their screening action can be regulated until the effect of the hull of the vessel has been neutralized.

The present invention will now be further described by refer nce to the accompanying drawing in which- Figure 1 shows one embodiment by way of example in which compensating loops are arranged to be moved on ways for variable adjustment with respect to the axis of the direction finding loop; and

Fig. 2 shows a modification in which the compensating loops are mounted on fulcrums.

Referring first to Fig. 1, the pillar or upright I of the frame or coil 2 has two diametrically 0pposite consoles or brackets 3,3, on which may be fixed two like loops, 5,4, disposed parallel in reference to the axis of the ship. The fixing means are adapted to facilitate adjustment of the distance or spacing, and they may consist, for instance, of slides. The loops may also be fixed at their base to a horizontal axis of rotation or fulcrum capable of inclining them in reference to the vertical plane.

The dimensions of the brackets 3, as may be seen from the drawing, are preferably made such that the supporting bases for the compensating loops 4 may be brought fairly close together so that, if desired, the planes in which the loops lie may be separated from the rotational axis of the loop 2 by a distance less than the equatorial radius of the rotatable loop. Furthermore, the loops 4 may be extended to the limits of the brackets 3 so as to be spaced away from the axis of the rotatable loop by a distance greater than the equatorial radius thereof.

Referring now to Fig. 2, I show a modification of the invention in which the compensating loops 4 may be mounted on fulcrum-like supports, whereby they may be inclined at suitable angles with respect to the axis of the rotatable loop 2. The fulcrum-like structure comprises bracket arms 6 and 7, each of which has pivot studs at the two ends thereof. The bracket arm 6 may be supported by a stationary top piece 5 which is shown supported by the pillar l. The bracket member 1 forms a connection between the member 6 and the base part of the loop 4. Frictional means, such as studs with wing nuts 8, may be provided for holding the bracket arms in a given position of adjustment. This structure, however, is not essential since any alternative forms of holding device may be employed if desired. The particular structure shown is, therefore, to be understood as merely an example of means for adjusting the compensating loops 4 in any desired angular relationship with the axis of the rotatable loop 2.

I claim:

1. In a radio-goniometer installed on ship: board a rotatable antenna coil and means for eliminating the quadrantal. error, comprising a combination of two loops each sufficiently large to surround said rotatable coil without touching the same and each of said loops being disposed substantially parallel to the ships axis and on opposite sides of the axis of said coil, and a device for fixing said loops provided with means for varying their distance'from said axis perpendicularly to their planes. 7

2. In a radio-goniometer for use on board of a vessel, a loop antenna mounted for rotation on a substantially vertical axis, means for eliminating the quadrantal error comprising a plurality of loops each having a plane of orientation that lies parallel to said axis of rotation of said antenna, and means for variably adjusting the distance'of separation of each of said planes of orientation from said axis of rotation anywhere between a minimum value less than the equatorial radius of said antenna and a maximum value greater than said equatorial radius.

3. In a radio goniometer for use on board a vessel, a rotatable antenna loop of a given diameter, a pair of parallel and symmetrically disposed compensating loops of 'a diameter sufliciently large to provide a clearance between themselves and said rotatable loop when said loops are brought' closer together'than the diameter of said rotatable loop and are disposed on opposite sides of the axis of said rotatable loop, and means including adjustable bases for supporting said compensating loops in any desired position with respect to the axis of rotation of said'rotatable loop.

4. A device in accordance with claim 3 and having horizontal platforms provided with ways in which said adjustable bases may be slid into position and then bolted down.

5. A device in accordance with claim 3 and having fulcrum -like supports for said compensating loops whereby they'may be inclined at suitable angles with respect to the [axis of said rotatable loop.

' ETTORE BELLINI. 

